I've met a few former Christians who just despise Christianity, in particular as Retro said, their church's interpretation of scriptures and blindly believing everything without question. Many come from evangelical Christian backgrounds.
If you react against anything, your views will most likely be distorted - in this case, they think Buddhism is "anything goes", you don't need Buddha to practice Buddhism, "Buddhism without beliefs", "if you see Buddha on the street, Kill him" (taking that famous saying out of context), Buddha was just a philsopher, etc. -- those are distorted views or perception of Buddhism.
Thanks for clarifying. I did misinterpret what you meant. I agree with what you say about "reaction" I prefer the idea of respond instead of react! My experience has been a bit different--I haven't come across too many or any once Christians that now hate Christianity--nothing as strong a reaction as hatred. But, then, I live in a pretty remote region.
But, I have seen folks pull away from their Christian upbringing and at first glance think Buddhism is the answer to everything they need based on one popular book on Buddhism they have read.